Electric valve converting system



June 1, 1937- c. A. sABBAH ELECTRIC VALVE CONVERTING SYSTEM OriginalFiled May 5, 1953 Fig. 2.

Inventor: i Camil A. Sabbah,

His Attorney.

i Reissued June l, 1937 y *Re 'I UNITED STATES PATENT OFFICE ELECTRICVALVE CONVERTING SYSTEM lOriginal No. 1,961,080, dated May 29, 1934,Serial No. 669,553, May. 5, 1933. Application for reissue May 23, 1936,Serial No. 81,547

17 Claims.

This invention relates to electric valve converting systems and moreparticularly to such systems suitable -for transmitting energy betweendirect 60 with one terminal of the high voltage circuit. It

is to be understood'that the terms "low voltage and high voltage do notimply any absolute values but only the relative values of the voltagesIn case the electric` valves I1-22, inc., are of current circuits ofdiiIerent voltages. of the two direct current circuits. The systemHeretofore, there have been proposed numerthus in eiect becomes a directcurrent autotranss ous electric valve converting systems for transformerin which the full windings of the reactor mitting energy between directand alternating device comprise the high voltage windings and currentcircuits, independent alternating current the portions included betweenthe alternating f circuits of the same or different frequencies, orcurrent terminals and the common terminal of lo direct current circuitsof diiTerent voltages. Apthe low voltage direct current circuit compriselo paratus of this latter type have, in general, comthe secondarywindings, or vice versa. prised separate inverting apparatus andrectify- For a better understanding of the invention, ing apparatuscoupled through a common .altertogether with other and further objectsthereof,

nating cunent circuit. In such an apparatus, the reference is had to thefollowing description takenergy passing from one direct current circuitto en in connection with the accompanying drawing l5 the other, ilowsthrough two independent groups and its scope will be pointed out in theappended o! valves so that the kv-a. rating of the equipclaims. In thedrawing Fig. 1 illustrates a conment as a whole is substantially greaterthan the verting system embodying the invention for transkv-a.transmitted between the two direct current mitting energy between twodirect current cir- 2 circuits,- cuits of different voltages, while Fig.2 shows a 20 It is an object of the invention to provide a new modiedform of the invention which is suitable and improved electric valveconverting system for supplying in addition an alternating current fortransmitting energy between two direct curload circuit. rent circuits ofdifferent voltages which will over-A Referring .now more particularly toFig. 1 of u come the above-mentioned disadvantages of the the drawing,there is illustrated an arrangement arrangements of the prior art, andwhich will be embodying my invention for transferring energy simple andreliable in operation. between a relatively high voltage `direct currentI.It is another object of the invention to provide circuit Ill-I I and arelatively low voltage direct an improved electric valve convertingsystem for current circuit I I-I2, having a common terminal transmittingenergy between direct current cir- II. This system includes an electricvalve concuits of dierent voltages in which the kv-a. ratvertingapparatus comprising a reactance deing of the equipment asa whole willnot substanvice I3 having a three-legged magnetic core tially exceed thekv-a. of the energy transmitted member, the several branches of whichcarry inbetween the circuits. ductive windings Il, I5 and I6.'Corresponding n -`In accordance with one form of the inventionterminals of the windings I4, I5 and I6 are con- 35 illustrated inFig'.l 2,'an electric valve converting nected to the direct currentterminal Ill through apparatus of the type disclosed in United States agroup of electric valves I1, I8 and I9, while the Letters Patent No.1,907,589 granted May 9, 1933 other terminals of these windings areconnected isused. That patent discloses a valve converting to the directcurrent terminal I I through a group 40 apparatus for transmittingenergy between diof valves 20, 2| and 22, respectively. Each of the 40rect and alternating current circuits and comseveral electric valvesI1-22, inc., is provided with 'prising a multi-legged reactor, theseveral an anode, a cathode and a control grid, .and may branches ofwhich carry inductive windings, corbe of any of the several types wellknown in the responding lterminals being connected to one side art,although it is preferred to use valves of the 5 of= the direct currentcircuit through one group gaseous or vapor electric discharge type. Each45 of;y valves and to the other side of the direct curof the windingsI4, I5 and .I6 is provided with rent circuit through a second group ofvalves. an intermediate terminal, these terminals divid- The alternatingcurrent circuit is connected to ing the several windings intoportionshaving the th'e electrical midpoints of the several inductivesame turn ratio. The intermediate terminals windings. In the presentinvention, illustrated of the windings Il, I5 and I6 are connected to 50in Figs. l and 2, intermediate terminals of the the several phaseterminals of a three phase Y- several inductive windings of the reactor'are connected inductive network 23, the electrical connected directlytogether or to the phase terneutral of whichis connected' to the directcurrent minals of. a polyphase alternating current netterminal I2through a smoothing reactor 24.

5;, work. The common connection of the inter- However in certain casesthe inductive network 23 55 mediate terminals or the neutral point ofthe may be omitted and the intermediate terminals inductive networkvforms one terminal of the of the windings I I, I5 and I6 connectedtogether low voltage direct. current circuit while the other to form oneterminal I2 ofthe direct current terminal of the low voltage circuit iscommon circuit.

current cannot be, commutated between them, under certain operatingconditions, by the grid circuits alone, and it is. necessary to connectthe capacitors 25, 25 and 21 in circuit with the windings I4, I5 and I5,respectively, either across the full windings, as illustrated, or acrossportions thereof. In order to render the several electric valves I1-22,inc., conductive in the proper sequence, their grids are connected totheir re'spective cathodes through current limiting resistors. I

2B and appropriate phase windings of the secondary .network 230i a gridtransformer, the primary Inetwork 30 of which is connected toanalternating current-circuit 3| of any suitable frequency.

The general principles of operation of the above described convertingapparatus per se will be well understood by .those skilled in the art.However, in accordance with the invention as illustrated in Fig. 1 itwill be apparent that the phase relation between the grid excitation ofthe valvesA I1, I3, I9 and valves 20, 2|, 22, energized through thephase windings 29 and 30 is such that the valves in the lower groupbecome conductive in advance of the 4corresponding valves of the uppergroup.` While the arrangement shown in `Fig. 1 provides a phase angie of120 between the time that the lower valves become conductive and thetime that the corresponding upper valves become conductive other anglesjust greater than 0`and slightly less thanV 180 may be employed.

In brief, neglecting the leakage reactancepf the device I3, the severalwindings Il, I5 and I5 serve tomaintain the total magnetomotive forceand that of each of the arms of the magnetic core structure I3 at aconstant value. In order to satisfy this condition, and the conditionthat all currentsflowing from one side of the direct current circuitmust equal those ilowing-to the other side (neglecting the auxiliarydirect current circuit II-I2) it has been demonstrated both analyticallyand experimentally that each of the several electric valves isconductive for 120 electrical degrees of each cycle, thefvalves becomingconductive in a predetermined sequence at a frequency equal to that ofthe alternating current circuit 3|, from which the grids of the severalelectric valves are controlled. In case the inductive network 23 is notconnected to an independent source of electromotiye force, the leakagereactance of the reactance device I3 and the inductive network '23 willtend to cause the current in the System to be slightly lagging withrespect to the alternating electromotive force of the network 23.

In operation the electromotive forces of the windings are in 'the properdirection to assist commutation and eiIect a transfer of. load currentbetween the valves. This may be accomplished, as is well understood bythose skilled in the art, by connecting the capacitors 25, 25 and 21across the windings Il, I5 and I6, respectively.

'I'he function performed in the operation oi',- the system by thethree-legged core structure I3, the windings Il, I5, I5 and theassociated capacitors 25, 25 and 21 perhaps will' be clarinedby thefollowing example of one cycle of operation of the valves associatedwith one leg of the core structure. In the arrangement shown, the gridexcitation supplied to the valves I1 and 20 is such that the valve 2liisconductive'for but meanwhile the valve I1 is nonconductive. In order tosupply energy to the valve 20, the capacitor 25, having been charged toa certain the gaseous or vapor electric discharge type, the

potential by previous operation, now discharges into the winding I4 soas to supply current to the Y anode of the valve 20. At the end of theconductivity ofthe va1ve'2II, the valve I1- becomes conductive and the.valve 2li now is nonconductive. Thus the current transmitted -by thevalve I1 serves. to store energy in the capacitor 25 during the periodof conductivity of this valve. At the end of the period of conductivityof the valve I1, the current is' transferred from this valve to thevalve I8 and during the conductivity of the valve I8. the valves I1 and2li both remain nonconductive. During the period when neither of thevalves I1 and 20 is conductive, 'the capacitor 25 discharges into thetransformer winding in order to maintain the required magnetomotive.force on this transformerl winding, and in doing so it reverses itspolarity so that it has the proper capacitors 25, 25 and 21 not onlyprovide commutating potentials to cause the transfer. of current betweenthe valves I1, IB and I5, but also operate as energy storage devices tosupply current to the anodes of the valves 2li, 2| and 22.

An alternating electromotive `force may be drawn from the intermediateterminals of the windings I4, I5 and I5. In'addition, however, it hasbeen shown both experimentally and analytically that a unidirectionalcomponent of. voltage exists between the electrical neutral of thenetwork 23 and the terminals III and I Iv and that the magnitude of thisunidirectional voltage bears a relation to the voltage of the directcurrent circuit Ill-II dependent on the number of turns of the lowerportions of' the windings I 4, I5 and I5 to that of the whole windings.An alternating electromotive force also exists In the windings of theinductive network23 and` this electromotive force may be utilized in anindependent alternating current circuit, if desired. This alternatingcomponent may be suppressed from the low voltage direct current.l

circuit II-I2 by means of the series reactor 2l or any other suitableiilter circuit. In case the network 23 is omitted, the operation of theremainder of the system is substantially the same. the `alternatingcomponents of voltage appearing across the inductive windings I4, I5,and Il andthe reactor 2l. Thus, in eil'ect, theabovedescribed lapparatuscomprises a direct current autotransformer, by means of which energy maybe transmitted between a relatively high voltage direct current circuitand a relatively low voltage direct current circuit, either of which maybe the supply circuit. The power transfer between the circuits may bevaried by varying the phase relation of potentials applied to the -gridsof the phase converting apparatus by means'of which 4 certain economy inthe capacitors may be secured. In this ilgure, two converting apparatusA and'Beach similar to the converting apparatus of Fig. 1 and eachhaving its corresponding elements similarly numbered with the subscripisa and b to identify the converting apparatus of which it is a part, arecombined to form a double three' phase converting system With such anarrangement, the electrical neutrals oi.' the networks 23a and 23h areinterconnected through an interphase transformer 32, the electricalmidpoint of which is connected to the direct current terminal -I2through the current smoothing reactor 2l. In this arrangement, a singlecommutating capacitor 33 may be connected across the interphasetransformer 32 to provide the necessary commutating electromotive force.In this arrangement, the capacitor` 33 operates at a third harmonicfrequency which enables a considerable reduction in its size and cost.In the system of Fig. 2 also, the networks 23a and 23h are illustratedas comprising primary networks of an output transformer, the secondary*Vnetwork 3l of which is connected to an alternating current load circuit35. In this manner, energy may be supplied from a high voltage directcurrent circuit to a low voltage di-rect current, or lvice versa, and atthe .same time energy may be supplied to anlalternating current circuitfrom .the same apparatus.

' While the preferred embodiments of the invention, asat present,considered, have been described, it will-be obvious to those skilled inthe art that various changes and modications may be-made withoutdeparting from the invention. and we therefore aim in the appendedclaims to cover all such changes and modiilcations as fall within thetrue spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal, an electric valveconverting apparatus connected across said high voltage circuitandincluding a plurality of inductive windings provided with'intermediate terminals, said intermediate terminals being interconnectedto form the other terminal of said low voltage circuit.

2. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal, an

`electric valve converting apparatus connected across said high voltagecircuit and including a plurality of inductive windings provided withintermediate terminals, and an inductive network interconnecting saidintermediate terminals and provided with an electrical neutral formingthe other terminal of said low voltage circuit; v 3. An electric valveconverting system' comprising a relatively ,high voltage direct currentcircuit, a relatively low voltage direct current circuit, said circuitshavinga common terminal, a plurality of pairs of electric valves, areactance deviceirovided with a plurality of windings, said valves andwindings being connected to form a plurality of paths across said highvoltage circuit, each including one of said windings and one of saidpairs of valves, a connection between intermediate terminals ofv saidwindings, forming the other terminal of said low voltage circuit, andmeans for rendering said valves conductive in a predetermined sequence.

4. An electric'valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currenteircuit, saidV circuits having a common terminal, a polyphase reactancedevice comprising an n-legged core structure having a winding on eachleg, a pair of groups of electricvalves, each connecting correspondingterminals of said windings to one side of said high voltage circuit,each of said windings being provided with an intermediate terminal, aplurality of other windings connected to form an n-phase winding systemin terconnecting said intermediate terminals and provided withanelectrical neutral forming the other terminal of said low voltagecircuit, and means for rendering said valves conductive in apredetermined sequence.

5. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal, a polyphase reactancedevice comprising an n-legged core structure having a winding on eachleg, a pair of groups of electric valves, each connecting correspondingterminals of said windings to one side f said high voltage circuit, eachof said windings being provided with an intermediate terminal, acommutating capacitor connected in circuit with each of said windings, aconnection between said intermediatey terminals forming the otherterminal, of said low voltage circuit, and means for rendering saidvalves conductive in a predetermined sequence.

`(i. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal, a polyphase reactancedevice comprising an vrl-legged core structure having a winding on eachleg, a pair of groups of electric valves, each connecting correspondingterminals of said windings to one side of said high voltage circuit,each ofsaid windings being provided with an intermediate terminal, acommutating capacitor connected in circuit with each of saidV windings,an n-phase inductive network interconnecting said intermediate terminalsand provided with an electrical neutral forming the other terminal ofsaid low voltage circuit, and means for rendering said valves conductivein a predetermined sequence.

'1. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said` circuits having a common terminal, an electric valveinverting apparatus connected across said high voltage circuit andincluding a plurality of inductive windings provided with intermediateterminals, a plurality of other inductive windings connected to form awinding system interconnecting said intermediate terminals, said windingsystem having an electrical neutral forming the` other terminal of saidlow voltage circuit, and an alternating current load circuit includingsaid winding system.

8. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal,

apolyphase reactance .-device comprising -au n-legged core structurehaving a winding on each leg, a pair of groups of electric valves, eachconnecting corresponding terminals of said windings to one side of saidhigh voltage circuit, each of saidwindings being provided with anintermediate terminal, a plurality of other windings connected to forman n-phase winding system interconnecting said intermediate terminalsand provided with an electrical neutral forming the other terminal oi'said low voltage circuit.' an alsaid winding system, and means forrendering said valves conductive in a predetermined sequence.

9. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct' currentcircuit, said circuits having a common terminal,

- a pair of polyphase reactance devices each comprising an n-legged corestructure having a winding on each leg, a pair of groups of electricvalves, each connecting corresponding terminals of said windings to oneside of said high voltage circuit, each of said windings being providedwith an intermediate terminal, and IL-phase inductive networkinterconnecting the intermediate terminals of the windings of each ofsaid reactance devices and provided with an electrical neutral, aninterphase inductive winding interconnecting said neutrals and itselfprovided with an electrical neutral forming the other terminal of saidlow voltage circuit, and means for rendering said valves conductive in apredetermined sequence.

10. An electric valve converting system comprising a relatively highvoltage direct current circuit, a relatively low voltage direct currentcircuit, said circuits having a common terminal, a pair of polyphasereactance devices each comprising an n-legged core structure having awind. ing on each leg, a pair of groups of electric valves, eachconnecting corresponding terminals of said windings to one side of saidhigh voltage circuit, each of said windings being provided with anintermediate terminal, an n-phase inductive network interconnecting theintermediate terminals of the windings of each of said reactance devicesand provided with an electrical neutral, an interphase inductive windinginterconnecting said neutrals and itself provided with an electricalneutral forming the other terminal of said low voltage circuit, acommtating capacitor connected across said interphase inductive winding,and means for rendering said valves conductive in a predeterminedsequence.

11. An electric valve converting system comprising a direct currentinput circuit,`a direct current output circuit, a' polyphase reactancedevice comprising an n`1egged core structure having at least on'ewinding on each leg, a group of valves interconnecting said reactancedevice with said input circuit, a second group 'of valvesinterconnecting said reactance device with said" output circuit, andmeans for controlling the conductivity of said valves. Y

12. An electric valve converting system comprising a direct currentinput circuit, a direct current output circuit, a polyphase reactancedevice comprising an n-legged core structure having at least one windingon'each leg, a capacitor for each leg connected across at least aportion of `said winding, a group of electric discharge valvesinterconnecting said reactance device with said' input circuit, a secondgroup of valves interconnecting said reactance device with said outputcircuit, and means i'or controlling the conductivity ofsaidvalves. n

13. An electric valve converting system comprising direct current `inputand output circuits, one of said circuits having a constant potentialcharacteristic and the other having a constant 20,891 Vternating currentAload circuit energized from current characteristic, an energy storageand transfer device including a plurality of capacitors connected inparallel to a plurality 0i' inductive windings, a plurality of electricvalves interconnecting said circuits with said device, and means forcontrolling the conductivities of said valves.

14. An electric valve converting system comprising a constant potentialdirect current circuit, a constant current direct current circuit, apolyphase reactance device comprising an nq legged core structure havinga winding on each leg, a group of electric discharge valvesinterconnecting said reactance device with said constant potentialcircuit, a capacitor for each leg of said reactance device andconnectedv across that portion of the winding associated with saidconstant potential circuit, a second group of electric discharge valvesinterconnectingsaid reactance device with said constant current circuit,and means for controlling the conductivity of said valves.

15. An electric valve converting system for l transmitting energybetween two circuits, one of said circuits being a direct currentcircuit, a polyphase reactance device comprising an n-legged corestructure having at least one winding on each leg,. a capacitor for eachleg being connectedacross at least a portion of said winding, a group otelectric discharge valves interconnecting said reactance device with oneof said circuits, a second group of electric discharge valvesinterconnecting said reactance device with the other of said circuits,and means for controlling the ,said circuits, an energy storage andtransfer device interconnecting said groups of valves, said devicecomprising an n-legged core structure having a winding on each leg and acapacitor forv each winding, said capacitors each being con- I nected inparallelwith a portion oi' the respective windings, and means forcontrolling the conductivities oi said valves.

17.- An electric valve converting system for transmitting energy betweena constant potential circuit'and a constant current circuit comprisingan energy storage andtransfer device having an n-legged core structureprovided with a capacitor and at least one inductive winding for eachleg.

said capacitors each being connected in parallel with a portion of itsassociated inductive winding, a group of controlled electric i dischargevalves connected between said energy transfer device and one of saidcircuits for controlling the flow of energy to be storedin said device,a second group ofcontrolled electric discharge valves connected betweensaid energy transfer device and said other circuit for controlling theiiow of energy from said device, and means for controlling theconductivities of said valves.

GENERAL ELECTRIC COMPANY. Assignee of Cami! A. Sabbah, Deceased. ByCHARLES E. TULLAR.

Vice President.

